WSEAS Transactions on Communications
Print ISSN: 1109-2742, E-ISSN: 2224-2864
Volume 12, 2013
A Novel Method of Walsh-Hadamard Code Generation Using Reconfigurable Lattice filter and Its application in DS-CDMA System
Authors: ,
Abstract: Walsh Hadamard codes are widely used as signature codes in the current wireless standards such as IS-95 CDMA, WCDMA, CDMA2000, and image transform applications. It is also used in conjunction with error correction algorithms for Reed-Muller codes and in dyadic invariant signal processing. In this paper, a novel method of generating Walsh Hadamard(WH) codes using lattice filter is proposed. The obtained results concur with the properties of WH code. The entire WH code set can be generated by changing the reflection coefficients without modifying the filter structure. This feature ensures reconfigurability and enables them to be used in software radio. Moreover, this reconfigurable structure can be used as a matched filter for multiuser detection in Direct Sequence Code division Multiple Access System (DS-CDMA). BER performance of a DS-CDMA system employing a correlator receiver and the proposed matched filter receiver for despreading is simulated in an AWGN channel and flat fading Rayleigh channel. Simulation results showing the generation of WH codes from the autoregressive model of first order Gauss-Markov process is also obtained.
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Keywords: Software defined radio, Walsh Hadamard codes, Lattice filter, Matched filter, Autoregressive model, Gauss-Markov process